Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Postharvest treatments against western flower thrips (Frankliniella occidentalis (Pergande)) and melon thrips (Thrips palmi Karny) on orchids.

Abstract

Postharvest treatments, including insecticidal dips, isopropyl alcohol dips, insecticidal fogs and hot-water immersion, were evaluated to control mixed infestations of Frankliniella occidentalis and Thrips palmi on Dendrobium orchid blossoms. The limiting factor for all postharvest treatments was phytotoxicity, characterized by a loss of vase life that differed among cultivars. Insecticidal dips and insecticidal fogs were less phytotoxic than hot-water immersion and isopropyl alcohol dips. Insecticidal fogs consisting of abamectin 20% e.c. and abamectin tank-mixed with Pyrenone e.c. (6% pyrethrins, 60% piperonyl butoxide) reduced the mean number of thrips per blossom by 93.8 and 92.3%, resp., and were non-phytotoxic. An insecticidal aerosol, Floragas (2% permethrin and 0.1% pyrethrum dissolved in high pressure liquified CO2) reduced thrips by 33-54% with no phytotoxicity. Insecticidal dips for 3 min with agitation reduced the mean number of thrips per blossom by 43.7-99.1%. Of the 12 insecticides and one surfactant tested, only chlorpyrifos 44.4% e.c., fluvalinate 22.3% d.f., and chlorpyrifos 50% d.f. were both effective and nonphytotoxic. Immersion in water at 49.5°C for 15 and 20 s reduced the mean number of thrips per blossom by 88.1% and 95.3%, resp. A 70% solution of isopropyl alcohol applied as a postharvest dip did not kill all thrips and was extremely phytotoxic to blossoms.